Evaluation of Soil and Foliar Insecticides for the Control of Colorado Potato Beetle in Potatoes, 2016

The objective of this experiment was to assess the efficacy of soil and foliar insecticides for the control of CPB on potatoes. The experiment was conducted at the Virginia Tech Eastern Shore Agricultural Research and Extension Center in Painter, VA and consisted of eight treatments arranged in an RCB design with four replicates. ‘Superior’ potatoes were planted on 18 Mar 2016. Plots were two-rows wide and 20-ft (6.1 m) long with unplanted guard rows on each side. Rows were planted on a 3-ft row center (0.9 m) with 11 inches (0.3 m) between plants, in a 6-tier field design with 8-ft (2.4 m) alleys between tiers and a 16-ft (4.9 m) center alley. All in-furrow and at drag-off treatments were applied in 900 ml of water at 19.8 gpa using a single nozzle boom equipped with an 8003 even flat spray tip powered by a CO₂-backpack sprayer at 30 psi. Furrows were cut using a commercial potato planter without the coulters on. All foliar treatments were applied with a 4-nozzle boom equipped with 110003VS spray tips spaced 20″ apart spraying two rows at a time and powered by a CO₂-backpack sprayer at 40 psi delivering 38 gpa. In-furrow treatments were applied on 18 Mar. Post-emergence (drag-off) treatments were applied on 18 Apr, and foliar treatments were applied on 10 Jun. All plots were maintained according to standard commercial practices.

On 25 May and 1 and 8 Jun, the number of all life stages of CPB was recorded per 10 stems per plot. On 14 Jun, percentage defoliation was estimated visually for each two-row plot. On 7 Jul, all potato tubers were mechanically harvested and weighed per plot. One hundred tubers were examined for wireworm and grub damage for each plot. Data were analyzed using ANOVA and were arcsine square root transformed prior to analysis. Means were separated using Tukey’s HSD at the 0.05 level of significance.

Colorado potato beetle pressure was moderate with 170 small larvae in the untreated check on 1 Jun (Table 1). On 1 Jun, all treatments had significantly fewer small and large larvae than the untreated check except Admire Pro at drag off (Table 1). On 8 Jun, all treatments had significantly fewer large larvae than the untreated check except Brigadier in-furrow, Brigadier at drag off, and Capture LFR + Brigadier (in furrow) (Table 1). All treatments had significantly lower percent defoliation from CPB feeding except Capture LFR + Brigadier (IF) fb Gladiator (foliar) and Admire Pro (at drag off). Potato plants quickly went down due to sudden wind and heat damage following the Gladiator application and further ratings were not possible past the defoliation rating of 14 Jun. Yields were not significant but all treatments had numerically higher yields than the untreated check except Admire Pro at drag off (Table 2). Percent wireworm and white grub damage were significant with all treatments having less percent damage than the untreated check except Admire Pro at drag off (Table 2). No signs of phytotoxicity were observed.

This research was supported by industry grants-in-aid of pesticide and/or research funding from FMC Corporation, Syngenta Crop Protection, and Bayer CropScience.